1. Filed of Invention
The present invention relates to reactive one-component coating-material and/or adhesive granules, to processes for preparing them and to their use.
2. Description of Related Art
Coating materials and hot-melt adhesives are known in a large number. Use is made, for example, of isocyanate-containing polyurethane coating materials and adhesives.
These polyurethane coating materials and adhesives comprise, for example, moisture-curing or moisture-crosslinking isocyanate-containing polyurethanes which are solid at room temperature and are applied in the form of their melt as an adhesive. The polymeric constituents of these adhesives are polyurethane groups and reactive isocyanate groups. Cooling in applied melt causes first a rapid physical setting of the hot-melt adhesive as a result of its solidification. This is followed by a chemical reaction of the remaining isocyanate groups with moisture from the ambient environment, to form a crosslinked, infusible material. For many applications these isocyanate-containing polyurethane adhesives are solvent-free and viscous. For further details relating to isocyanate-containing polyurethane polymers reference may be made to H. F. Müller, H. Müller, “Shaping Reactive Hotmelts Using LMW Copolyesters”, Adhesive Age, November 1987, pages 32 to 35.
Alternatively it is possible to prepare reactive coating materials and adhesives on the basis of silane-functional polymers, too.
Compositions based on isocyanate-containing or silane-functional polymers for coating materials and adhesive materials of this kind are known from patent application WO 00/47687 A1, which describes a process for continuous preparation of a multi-component coating and adhesive material based on isocyanate-terminated or silane-functional polymers and also the use thereof for adhesive bonding or coating, respectively. These materials are prepared by mixing the individual components, in particular with heating to bring them into a liquid state, and are then supplied immediately for their use. In the case of an adhesive material based on isocyanates the two components are composed on the one hand of a relatively high molecular mass starting polymer and on the other hand of a reactive isocyanate-terminated crosslinker. When an adhesive or coating material based on silane-functional polymers is used a reaction takes place between a relatively high molecular mass starting polymer and a reactive silane-functional crosslinker.
The use of multi-component systems in the preparation of hot-melt adhesive and coating materials is known. On this point reference may be made, for example, to “Handbook of adhesives”, 2nd Edition, p. 581 ff. and to “The ICI polyurethanes book”, 2nd Edition, p. 93 ff. In the case of these multi-component systems there is exclusively a reaction of the components with one another and, after reaction has taken place, there is no longer any remaining reactivity for subsequent reactions with, for example, moisture.
For certain applications, however, there may be a desire to use coating and adhesive systems which are in one-component form, since these do not require mixing prior to their application. Mixing of the individual constituents of a multi-component system, on the other hand, is generally more laborious and has to be integrated into a processing operation; this generally necessitates complex additional apparatus, such as metering devices for the different components, for example, and in addition there is in particular a risk of metering errors. Moreover, rapid processing of the multi-component systems prepared is necessary, so that the constituents, especially under the influence of moisture, do not react before the desired application.